However, relying on cloud computing comes with drawbacks, including privacy, security, and reliability concerns. So there is now growing interest in open-source cloud-computing tools, for which the source code is freely available. These tools could let companies build and customize their own computing clouds to work alongside more powerful commercial solutions.

One open-source software-infrastructure project, called Eucalyptus, imitates the experience of using EC2 but lets users run programs on their own resources and provides a detailed view of what would otherwise be the black box of cloud-computing services.

Another open-source cloud-computing project is the University of Chicago's Globus Nimbus, which is widely recognized as having pioneered the field. And a European cloud-computing initiative coordinated by IBM, called RESERVOIR, features several open-source components, including OpenNebula, a tool for managing the virtual machines within a cloud. Even some companies, such as Enomaly and 10gen, are developing open-source cloud-computing tools.

Rich Wolski, a professor in the computer-science department at the University of California, Santa Barbara, who directs the Eucalyptus project, says that his focus is on developing a platform that is easy to use, maintain, and modify. "We actually started from first principles to build something that looks like a cloud," he says. "As a result, we believe that our thing is more malleable. We can modify it, we can see inside it, we can install it and maintain it in a cloud environment in a more natural way."

Reuven Cohen, founder and chief technologist of Enomaly, explains that an open-source cloud provides useful flexibility for academics and large companies. For example, he says, a company might want to run most of its computing in a commercial cloud such as that provided by Amazon but use the same software to process sensitive data on its own machines, for added security. Alternatively, a user might want to run software on his or her own resources most of the time, but have the option to expand to a commercial service in times of high demand. In both cases, an open-source cloud-computing interface can offer that flexibility, serving as a complement to the commercial service rather than a replacement.

Indeed, Wolski says that Eucalyptus isn't meant to be an EC2 killer (for one thing, it's not designed to scale to the same size). However, he believes that the project can make a productive contribution by offering a simple way to customize programs for use in the cloud. Wolski says that it's easier to assess a program's performance when it's possible to see how it operates both at the interface and from within a cloud.

Wolski says that Eucalyptus will also imitate Amazon's popular Simple Storage Surface, which allows users to access storage space on demand, as well as its Elastic IP addresses, which keeps the address of Web resources the same, even if the physical location changes.

Ignacio Llorente, a professor in the distributed systems architecture group at theUniversidad Complutense de Madrid, in Spain, who works on OpenNebula, says that Eucalyptus's main advantage is that it uses the popular EC2 interface. However, he adds that "the open-source interface is only one part of the solution. Their back-end [the system's internal management of physical resources and virtual machines] is too basic. A complete cloud solution requires other components." Llorente says that Eucalyptus is just one example of a growing ecosystem of open-source cloud-computing components.

Wolski expects many of Eucalyptus's users to be academics interested in studying cloud-computing infrastructure. Although he doubts that such a platform would be used as a distributed system for ordinary computer users, he doesn't discount the possibility. "You can argue it both ways," he notes. But Wolski says that he thinks some open-source cloud-computing tool will become important in the future. "If it's not Eucalyptus, I suspect [it will be] something else," he says. "There will be an open-source thing that everyone gets excited about and runs in their environment."

FOREVER BRUCE LEE

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Great Minds Have Similar Thoughts

Champions aren't made in gyms, champions are made from something they have deep inside them - a desire, a dream, a vision. They have to have last-minute stamina, they have to be a little faster, they have to have the skill and the will. But the will must be stronger than the skill.-Muhammad AliI'll be more enthusiastic about encouraging thinking outside the box when there's evidence of any thinking going on inside it.- Terry PratchettNot to be absolutely certain is, I think, one of the essential things in rationality.- Bertrand RussellWhat we think, or what we know, or what we believe is, in the end, of little consequence. The only consequence is what we do.Sometimes what's right isn't as important as what's profitable.- Trey Parker and Matt StoneThere are only two kinds of people who are really fascinating: people who know absolutely everything, and people who know absolutely nothing.- Oscar WildeSometimes I lie awake at night, and I ask, "Where have I gone wrong?"/ Then a voice says to me, "This is going to take more than one night."- Charles M. SchulzThere is nothing worse than aggressive stupidity.- Johann Wolfgang von GoetheThe significance of man is that he is insignificant and is aware of it.- Carl BeckerA lie can travel halfway around the world while the truth is putting on its shoes.- Mark Twain"If you know how to spend less than you get, you have the philosopher's stone." So said Benjamin Franklin more than 200 years ago. How much easier it is to be critical than to be correct.- Benjamin DisraeliOf course the game is rigged. Don't let that stop you--if you don't play, you can't win.- Robert HeinleinAbility will never catch up with the demand for it.- Malcolm ForbesNo man remains quite what he was when he recognizes himself.- Thomas MannNo man needs a vacation so much as the man who has just had one.- Elbert HubbardThere is no pleasure in having nothing to do; the fun is in having lots to do and not doing it.- Mary Wilson LittleBooks to the ceiling,/ Books to the sky,/ My pile of books is a mile high./ How I love them! How I need them!/ I'll have a long beard by the time I read them.- Arnold LobelLeif Ostling said in a statement that his comments about Germany had been "interpreted in a way that was not intended."If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts he shall end in certainties.- Sir Francis Bacon"It's not the voting that's democracy, it's the counting."- Tom StoppardElections are won by men and women chiefly because most people vote against somebody rather than for somebody.- Franklin P. AdamsInvention is the mother of necessity.- Thorstein VeblenDon't try to solve serious matters in the middle of the night.- Philip K. Dick